SeriesLines Object [Excel 2003 VBA Language Reference]
Represents series lines in a chart group. Series lines connect the data values from each series. Only 2-D stacked bar, 2-D stacked column, pie of pie, or bar of pie charts can have series lines. This object isn't a collection. There's no object that represents a single series line; you either have series lines turned on for all points in a chart group or you have them turned off.
Using the SeriesLines Object
Use the SeriesLines property to return a SeriesLines object. The following example adds series lines to chart group one in embedded chart one on worksheet one (the chart must be a 2-D stacked bar or column chart).
With Worksheets(1).ChartObjects(1).Chart.ChartGroups(1) .HasSeriesLines = True .SeriesLines.Border.Color = RGB(0, 0, 255) End With
If the HasSeriesLines property is False, most properties of the SeriesLines object are disabled.